In at least some computed tomograph (CT) imaging system configurations, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as the "imaging plane". The x-ray beam passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. X-ray sources typically include x-ray tubes, which emit the x-ray beam at a focal spot. X-ray detectors typically include a collimator for collimating x-ray beams received at the detector. A scintillator is located adjacent the collimator, and photodiodes are positioned adjacent the scintillator.
Multislice CT systems are used to obtain data for an increased number of slices during a scan. Known multislice systems typically include detectors generally known as 2-D detectors. With such 2-D detectors, a plurality of detector elements form separate channels arranged in columns and rows. Each row of detectors forms a separate slice. For example, a two-slice detector has two rows of detector elements, and a four-slice detector has four rows of detector elements. During a multislice scan, multiple rows of detector cells are simultaneously impinged by the x-ray beam, and therefore data for several slices is obtained.
Multislice detectors are typically segmented into a series of individual scintillator cells in the X and Z axes. These scintillator cells can be separated by narrow gaps of only a few micrometers between adjacent cells. The gaps are filled with a light reflecting material. The detector elements could accept off-axis, or scattered, x-ray beams which decrease contrast resolution and increase image artifacts.
Accordingly, it would be desirable to provide a detector array that collimates and separates the x-ray beams toward individual detector elements to reduce scatter and spectral artifacts. In addition, it is desirable to provide a detector array collimator that protects the gaps between the elements from x-ray beams so that radiation damage, beam hardening, punch through noise and spectral effects of the light reflecting material is minimized.